I'm not quite sure I understand your thoughts correctly but I'll give you my opinion anyway. Being drunk is not a criminal offence in Finland. However, 10 intoxicated people were placed in jail/custody, obviously because they were too drunk to take care of themselves.

In addition to these 10 people, 4 people were arrested on criminal charges. Rikosperusteisesti is an adverb formed from the rather rare adjective rikosperusteinen.

It's not very beautiful to drop the verb here, because the adverb rikosperusteisesti should actually be juxtaposed with another adverb, and in "10 liikaa nauttinutta jouduttiin ottamaan säilöön" there is no adverb.